At this point, police are reluctant to call Mastracola's disappearance suspicious because she is an avid hiker who often leaves town for days.

"We are trying to figure out if she went out of state or if she turned her phone off and just didn't want to talk to anyone. We're looking into airlines, to see if maybe she bought a ticket and took a plane ride somewhere," said Chief Shawn Payne.

The fact that she hasn't checked in at work or returned calls from her roommate or family is raising concern.

They say her phone was on until about 9:00 p.m. Wednesday night, but now it is either off or has died.

"It's kind of concerning why she is not contacting anyone. Even if she wasn't making it to work, why is she not contacting her employer? She is a reliable employee," said Chief Payne.

Both the Delaware County District Attorney's office and the Criminal Investigation Department are now involved in the case.

Anyone with information on Mastracola's whereabouts is asked to call Millbourne Police at 610-352-1450 or 911.